Machine for perforating sheet material



Aug. 20, 1935. w. T. MILLER MACHINE FOR PERFORATING SHEET MATERIAL FiledFeb. 7, 1934 \M an ex /1,. 'IIIIIIIIII 11 1'! I 2 TH ,dzllllllluiififmli 7 71 I II/IIIIIIIIIIIIIIII Patented Aug. 20, 1935 2,011,645MACHINE ron rnarona'rmo snnn'r MATERIAL Walter T. Miller, Gloucester,Mass. Application February 1, 1934, sci-n1 No. 710,120

8 Claims.

My invention relates to machines for perforating sheet material by meansof electric sparks.

In the processing of certain imperforate sheet material, it is foundadvisable to perforate the material with minute holes to facilitateevaporation, and to prevent sweating, and the object of my invention isto provide means by which this may he done by producing successive linesof perforations across the sheet material, by means of electric sparksacross a spark gap through which the sheet material is moved.

My invention consists in the novel construction of a machine and themethod of operation to accomplish my object. In the accompanyingspecifications and claims and the drawing forming a part thereof, I havedescribed and illustrated a preferred embodiment of my inventiontogether with two modified forms that maybe used, but do not confinemyself to these embodiments as other modifications may be made withinthe scope of the appended claims.

In the drawing,

Fig. 1 is a sectional elevation of a machine for the purpose specifiedin which my invention is embodied.

Fig. 2 is a plan of the same.

Fig. 3 is an enlarged fragment showing one means for conveying theelectric current to terminals.

Fig. 4 is a modification in which one terminal is reciprocated inoperative relation to a fixed terminal of extended form.

Fig. 5 is a modification in which a pair of terminals are reciprocatedacross the path of movement of the sheet material.

Referring to the drawing,

The reference characters refer to like parts on all figures and in themodifications, Figs. 4 and 5, the indices, anda refer to elementssimilar in function to the main characters.

I! is a machine frame on which is rigidly mounted the goose-neck H. Inthis goose-neck is journalled the hollow shaft l2, to one end of whichis secured the disc i3, and to the other the driving pulley I", drivenfrom a source of power not shown, by the belt It, or by an equivalent.to rotate the disc at a relatively high speed. Insulated in the disc I!are spark points l4, l4 and II" equidistant from the axis of rotationand preferably spaced equi-angular. The disc may be of insulatingmaterial, or of conducting material with the spark points insulatedtherefrom. The spark points are electrically connected by suitable,insulated means to the main conductor i6, andonemeansisshowninFig. 1andin theenlarged plan, Fig. 3. Referring particularly to Fig. 3, theconductor It extends through and is insulated from the shaft l2, andterminates in a hub l1. Brushes l8 insulated from the disc it, aremounted within the hub i9 thereof, and from 5 The two conductors l6 and20, the latter being formed as an extended terminal, are connected byrespective wires 2|, 22, to an induction coil 23 in circuit by means ofmains 24, 25, with a source 90 of electric power not shown. Potential isbuilt up by the induction coil, and as the disc is rotated, a successionof electric sparks occurs as and while each spark terminal opposedterminal, which is formed concentric with the path of movement of themovable ter- The sheet material A is drawn over the 20 and between itand the path of rodrawn from a reel 3|. As the machine is operated, aseries of sparks from each movable terminal perforates the moving sheetand forms successive arcs of minute perforations laterally of the sheet,the relative speed of rotation of the movable terminals and the movementof the sheet ma- 40 be in the form of arcs laterally across the sheet,but straight lines of perforations may be made as shown in modificationshown in Fig. 4. In this case, I mount one terminal W in a crosshead Ifsuitably mounted in a sliding bearing i2, and adapted to be reciprocatedby means of the crank 32 and pitman 33, over a fixed terminal 20, theshaft 34 being mounted in the gooseneck I I. The sheet A may be moved inthe manner above explained, in which case the lines of perforationswould be at an angle with the selvage of the sheet, but if the sheet ismoved intermittently, the lines may be arranged normal to the selvage,in either case separated according to the movement of the sheet.

In Fig. 5, I mount the terminal 20a in the crosshead Ito, and the twoterminals W and Ila are reciprocated in unison, by means slmilarto thosedescribed as applying to Fig. 4, the elements being similar andidentified by the index a.

Having thus described my invention, I claim:

1. In a machine for perforating sheet material by means of electricsparks, a terminal element, movable laterally in a fixed path and inparallel relation to a sheet of material, and in such relation to ablade like terminal extended laterally, that a spark gap of unvariedwidth is formed therebetween when the terminals are opposed.

2. In a machine for perforating sheet material by means of electricsparks, the combination of a terminal element movable laterally and in afixed path in such relation to a blade like terminal, that a spark gapof substantially unvaried width is formed between the former and theedge of the latter when the terminals are in opposition.

3. In a machine for perforating sheet material by means of electricsparks, the combination of a terminal element movable laterally in afixed path in such relation to a fixed terminal that a spark gap ofsubstantially unvaried width is formed therebetween when the terminalsare in opposition, one terminal being a blade like extension in thedirection of movement of the movable terminal.

4. A machine for perforating sheet material by means of electric sparks,including a pair of terminal elements, one fixed, the other relativelymovable laterally in a fixed path, and one terminal being a blade likeextension and in such relation to the other, that a spark gap ofsubstantially unvaried width is formed between the former and the edgeof the latter, while the movable terminal is opposed to the other.

5. In a machine for perforating sheet material by means of electricsparks, the combination of a blade like fixed terminal extended in alateral plane, and a terminal movable in a fixed path in a planeparallel thereto and in such relation that a spark gap of substantiallyunvaried width is presented while the movable terminal is movedlaterally in opposition to the fixed terminal.

6. In a machine for perforating sheet material by means of electricsparks, the combination of a terminal rotatable about a fixed axis, anda fixed terminal in the same radial relation to the said axis, andseparated from the plane of rotation of the movable terminal to form aspark gap of unvaried width when the terminals are opposed.

7. In a machine for perforating sheet material by means of electricsparks, the combination of a terminal rotatable about a fixed axis and aterminal extending concentrically with said axis and in a plane parallelwith and separated from the plane of rotation of the movable terminal bya spark gap of substantially unvaried width while the terminals areopposed.

8. A machine for perforating sheet material by means of electric sparks,including a plurality of terminals movable in a path concentric with afixed axis; a fixed terminal concentric with said axis and at the sameradial distance therefrom, the plane of rotation of the rotatingterminals being parallel to the fixed terminal and separated therefromto provide a substantially unvaried width of spark gap while eachmovable terminal is opposed to the fixed terminal; means for supplyingelectric current of sufiicient potential to provide a succession ofsparks between the rotated terminals and the fixed terminals while theyare opposed.

WALTER T. MILLER.

